First of all, you have to understand that community fees are to cover the cost of maintaining and repairing community areas and services - they never include any maintainence or repairs to private individual homes, except, as you state, when for example a leaking communal pipe causes damage to an individual home.
In most communities like yours, at the agm, a total budget for the year is agreed upon, factoring in known projected costs, such as electricity, lift maintainence, insurance, cleaning, administration etc., and probably a fund for ongoing repairs and unforseen circumstances. It's possible that each of your blocks would have an individual budget, but morelikely that all four blocks are treated as one community with a common budget. The budget is worked out by the president and/or administrator, then voted on and approved at the agm, and should be included with the minutes that you received. From this, you should be able to identify exactly where the money is intended to be spent.
Each individual property within the community pays a quota, or percentage, of the overall budget. This quota is set out in your escritura (deed) by law. It is usually based on the square meterage of your property. The bigger the property, the more you pay. Basically much the same as council tax in that respect.
Hope this explains things for you. If you're really interested, you can read the Horizontal Property Law in English here. Once you've got it sussed, you'll be perfectly prepared to volunteer as the next president!